1. Field of the Invention
The present invention relates to a preparation process of trisilylamine (N(SiH3)3).
2. Description of the Related Art
Trisilylamine (which may hereinafter be abbreviated as “TSA”) is known as a compound useful as a silicon source in film formation using CVD. For example, it is reported in U.S. Pat. No. 4,200,666 that a high film formation rate and high film uniformity can be achieved by using TSA for the formation of a silicon nitride film. It is also reported in JP 2006-16641A that by using TSA as a silicon source for the formation of a silicon oxynitride film comprising a high-dielectric-constant metal, a carbon impurity level can be lowered and the metal content can be controlled more easily compared with film formation using silane and an organic amide compound.
In a general synthesis process, TSA is obtained from monochlorosilane and ammonia. Monochlorosilane is obtained as a trace by-product of the synthesis of dichlorosilane or trichlorosilane and it is not mass-produced as an intended product. In addition, similar to monosilane, it is difficult to treat monochlorosilane safely so that according to many conventional reports, TSA is synthesized from monobromosilane (for example, Journal of the American Chemical Society, 76, 4631-4636(1954)).